Volume imaging data has become prevalent in medical imaging modalities such as ultrasound imaging, magnetic resonance imaging, computed tomography, and Optical Coherence Tomography (OCT). Volume data has brought innovation to the medical field, making it possible to safely and noninvasively directly observe the internal structure of a body, in particular of a human body. In recent years, volume rendering image processing techniques have been used to reduce the volume data to images displayed for medical diagnosis. Volume rendering enables visualization of three-dimensional structures by displaying a 2D projection of the 3D structure on commercially available 2D display.
Optical Coherence Tomography (OCT) is a technology for performing high-resolution real time optical imaging in situ. OCT is an optical measurement and imaging technique using either low-coherent light from a broadband source or sweeping light from a tunable laser to create interference signals measuring backscatter intensity at depths along a sample path. This depth profile is commonly called an “A-scan”. Laterally scanning the sample beam over a series of adjacent A-scans synthesizes cross-sectional images, creating a 2-D tomogram commonly called a B-scan. Typically, volumes are acquired by laterally scanning the sample beam over a series of B-scans; however alternative scan patterns, such as a spiral scan pattern, have been suggested to acquire volume data.
Evaluation of biological materials using OCT was first disclosed in the early 1990's (see U.S. Pat. No. 5,321,501, Swanson, et al.). More recently it has been demonstrated that frequency domain OCT (FD-OCT) has significant advantages in speed and signal to noise ratio compared to time domain OCT (Leitgeb, R. A., et al., (2003) Optics Express 11:889-894). In Spectral Domain OCT (SD-OCT), sometimes referred to as Frequency Domain OCT (FD-OCT) and sometimes also referred to as Spectral Radar (Hausler, G and Linder, M W, Journal of Biomedical Optics Vol. 3 No. 1 (1998) 21-31), the measurement is achieved by examining the spectral content of the interference pattern out of the interferometer.
Volume data is reduced from 3-D to 2-D for display on a monitor or when printed on paper. In U.S. Pat. No. 7,301,644, Knighton et al. disclosed a method for reducing 3-D data for 2-D display called en-face imaging. This technique takes the volume data (or an interesting volume subset of the 3-D dataset) and integrates the data along each A-line, creating a 2-D image from the 3-D dataset. This technique has proven to be a very useful tool for viewing the OCT volume data. In light of the above, there is a need in the art for additional methods for viewing 2-D images of 3-D volume OCT data. The present invention provides such additional methods for creating 2-D images from 3-D volume data sets to display medically relevant information.